1. Field of the Invention
The present invention generally relates to the tracking of movement of people and objects using wireless communication links and, more particularly, to combined tracking of and communication with people and objects using a widely available and well-developed communications medium.
2. Description of the Prior Art
Radio Frequency Identification (RFID) systems have been known for a number of years, particularly in the field of theft deterrence. Many retail establishments now mark goods with a removable tag or include a permanent device in or on the goods which can be deactivated by a magnetic field or other arrangement. Tags which have not been deactivated or removed are then detected at some point of egress from the store by radio frequency interrogators positioned to detect active tags brought into proximity therewith.
RFID systems are not at all limited to theft deterrence and may be used for a wide variety of applications ranging from, for example, inventory control to secure location access control to global supply chain problems. Any object, animal or person with which a detectable tag can be physically associated can be tracked and its location reported to any desired level of accuracy or resolution with a suitably designed RFID system. Depending on the application, the tags may be active or passive (e.g. powered or unpowered) and may or may not have the capability of being separately identifiable, either uniquely or in groups/categories, or other capabilities. Radio interrogators may also be of widely varying configurations, depending on the intended application.
Unfortunately, current RFID systems are generally custom designed for particular application and/or rely on proprietary, dedicated hardware. Therefore, such systems can be expanded or modified only with substantial difficulty and cannot be adapted for any other data intensive application. Further, in general, RFID products from different vendors are not interoperable and, moreover, may interfere with or have their performance degraded by other radio frequency applications, including other RFID systems, used in the same environment. The geographic scope of the RFID system is generally fixed with the system design and, in general, the detectable range of tags from radio interrogators is very limited, often to a few feet or meters.
Local area and wide area networks are known for providing communications between data processing devices such as personal computers to allow them, for example, to access a common data base. Such networks may be hard-wired or wireless or a combination thereof. Wireless portions of a local or wide area network communicate with individual terminals through radio frequency transmitters and receivers which are spatially separated and generally referred to as access points. The network has the capability of tracking the particular terminals with which communications can be conducted from a given access point at any given time.
It should be recognized that RFID systems can interfere with wireless portions of local and wide area networks and other radio frequency systems and vice-versa. That is, for example, a RFID system may preclude use of a wireless portion of a LAN or WAN (hereinafter collectively referred to as networks) in certain locations of a facility. Further, the detectable tag of an RFID system may compromise other devices or arrangements that rely on radio frequency communications, particularly compromising reliable communications between terminals and access points of a network.
It should also be recognized that while RFID systems and wireless portions of networks are similar enough in some ways to interfere with each other, the proprietary nature of the former and the intended function of the latter does not permit combined functions to be realized. For example, while a wireless portion of a network may have a rudimentary capability to track and/or switch the access point for communication with a particular terminal, it cannot generally report the location of the assets that such terminals or particular operators which particular terminals may represent, much less track assets represented by equipment connected to a given terminal which may communicate with a central server or other terminals through a wireless portion of a network. Conversely, RFID systems cannot provide data communications using standard wireless data networking protocols, such as IEEE 802.11. Special purpose transmitter/receiver devices, known as interrogators, are equipped to merely sense the proximity of identifiable tags or to engage in limited read/write data traffic with the tags using protocols that preclude the inclusion of other network-aware devices participating in the communication.